In recent years, there is a growing trend to save power consumption at home and office, in consideration of increasing electric power demand and the global environment. Along with the growth of the energy saving trend, efforts are made to frequently turn off electronic devices, to review the temperature set for air conditioning, and the like.
Various methods for measuring power consumption are proposed to figure out how much energy saving is actually achieved by such efforts.
However, any one of these methods has difficulty in accurately measuring power consumption of each of electronic devices.
For example, there is proposed a method in which a terminal for measuring power consumption is provided to an outlet at home, and measures the power consumption of an electronic device connected to the outlet. When a power strip is connected to one wall outlet and is connected to multiple electronic devices, however, this method has a problem that the power strip is incapable of measuring the power consumption of each of the electronic devices individually even though the power strip can measure the total power consumption of the multiple electronic devices.
In another method, an electric current sensor for measuring a power consumption is provided to a power supply line upstream of power division by a distribution board in a house. This method, however, has no way to figure out how much electric power is consumed in each of power supply lines downstream of the power division by the distribution board.
Note that, techniques related to the present application are disclosed in Japanese Laid-open Patent Publication Nos. 09-84146, 11-313441, and 2001-663330.